36 PROCEEDINGS OF THE XATIOXAJL MUSEUM, vol.63. 



the Pacific slope of the Andes and as far east as the Athmtic coast. 

 These records indicate that the geographical range of the family is 

 practically coextensive with that of the neotropical region. 



Vertically, specimens have been taken from practically sea level 

 along the coast of the Province of Buenos Aires, Argentina, up to 

 La Raya Pass, 4,267 meters (14,000 feet), in Peru. The extreme 

 record for this elevation for a species on a cavy, Cavia tschitdii. 

 Since apparently all species of cavies are infested with Gyropids, 

 and these rodents are known to range from sea level to this altitude 

 of 4,267 meters, it may, with a high degree of probability, be inferred 

 that the Gyropidae have this great vertical range. 



The single record from Europe for Allogyropus turhinatus 

 (Piaget) on Arctomys marmotta is to be questioned, as being an 

 authentic one for the host species and locality of this louse. The 

 host given is a Sciurid, and not only is this the only host species ever 

 reported for this family of rodents, but the extensive examinations 

 of the rodents of the family Sciuridae by several workers have failed 

 to reveal any infesting Gyropidae. It should also be noted that 

 up to the present no records of Gyropids from Sciurid hosts have 

 been made in the neotropical region where these mammals extend 

 far into the range of the Gyropid parasites. 



HOST DISTRIBUTION. 



More remarkable than the restriction of this Mallophagan family 

 in its geographical distribution to a single region is its extension in 

 its host distribution to diverse mammalian groups. These groups 

 include certainly three different orders, and possibly four, the orders 

 being: Edentata, Eodentia, Primates, and Ungulata. One of these 

 orders, the Rodentia, however, includes the vast majority of the 

 species; while of the remaining orders Ungulata has two species; 

 Primates, one, and Edentata possibly one. Not only is the family 

 Gyropidae concentrated chiefly on rodents but even in this order 

 it is found only on four or possibly five or six families. It is on 

 the Caviidae and the Octodontidae that the Gyropidae find their 

 most favored hosts, members of these two families frequently sup- 

 porting two or even three G3^ropid species. 



That Gyropids normally infest edentates should be questioned. 

 The single record of Gyropus hispidus Nitzsch from the sloth, 

 Bradypvs fridactylus, is based upon a single specimen from a dried 

 skin. In order to establish, if possible, the validity of this record the 

 writer has gone over the entire collection of several scores of sloth 

 skins in the United States National Museum. During all this search 

 not a single louse or nit was found. Added to this negative evidence 

 is that given by Dr. W. M, Mann, who during his trip with the Mul- 



